Apparatus for making heat sealable wrapper



April 24, 1962 A. v. SHANNON 3,030,915

APPARATUS FOR MAKING HEAT SEALABLE WRAPPER Filed April 30, 1957 3Sheets-Sheet 1 INVENTOR.

ARTHUR VERNON SHANNON ATTURNEE April 24, 1962 A. v. SHANNON APPARATUSFOR MAKING HEAT SEALABLE WRAPPER Filed April 50, 1957 3 Sheets-Sheet 2{HOT MELT I RESERVOIR I L RUBBER PATTERN ROLL r l l l l I l l l l I I IINVENTOR.

ARTHUR VERNON SHANNON April 24, 1962 A. v. SHANNON APPARATUS FOR MAKINGHEAT SEALABLE WRAPPER Filed April 30, 1957 3 Sheets-Sheet 3 INVENTOR.

ARTHUR VERNON SHANNON ATTORNEYS.

United States atent 3,030,915 APPARATUS FOR MAKING HEAT SEALABLE WRAPPER7 Arthur Vernon Shannon, Princeton, N.J., assignor to Pacon Research &Development Corporation, New York, N.Y., a corporation of Delaware FiledApr. 30, 1957, Ser. No. 656,069 2 Claims. (Cl. 118-202) The inventionrelates to a method and apparatus for making a heat scalable wrapper orliner strip of metal foil or other suitable material for delivery to awrapping machine in continuous lengths as the strip is being prepared.

Metal foil, and especially aluminum foil, is widely used as an outerwrapping for food products and other goods packaged in paperboardcartons. Generally the foil is paper-backed and its metal face isprinted or lithographed to describe and advertise the contents of thepackage. Among the reasons for use of paper-backed aluminum foil is thatit is quite impervious to moisture and is therefore a help in keepingproducts fresh and marketable. Where this is to be considered, it isalso regarded essential to provide an effective seal at the edges of thewrapper. One way of sealing the Wrapper has been to provide a layer ofwax over the paper side of the foil composite with an added layer ofpaper over the wax, and to apply heat to the outside of the wrapperwherever a seal is wanted. The heat melts the wax which bleeds throughthe layer of paper and then solidifies to form an adhesive film betweenoverlapping edge portions of the wrapper. While this method has beenused very widely, it has a number of disadvantages. Frequently the waxbleeds through where a seal is not wanted, as between the wrapper andthe paperboard carton, creating an adhesive bond which may beobjectionable. Because the added layer of wax and paper extend over theentire area of the wrapper, the sealing means is not confined to theareas to be sealed. This is quite uneconomical and adds to the cost ofthe package. Besides, there is no way of getting a seal in the placeswhere the outer face of the wrapper is folded over against itself asoccurs in the diagonal folds at the corners of the wrapper and Whereverone folded section is brought against another. In such places the waxcannot bleed through to provide a seal. Yet they are the very placeswhere a seal can be most important; and the unsealed edges can catch andtear so that the package becomes unsightly and may even come unsealed.It is an object of my invention to overcome these and otherdisadvantages of the wrappers and wrapping methods generally usedheretofore.

Kbcording to my invention, a melted thermoplastic adhesive material isapplied in a special manner to predetermined sealing areas of the faceof the wrapper (or liner) strip of metal foil or other suitable materialas it is being prepared for delivery to a wrapping machine. Manyproblems were encountered before it was discovered how to apply hotmelted adhesive to the wrapper in a pattern designed for the sealingareas, and in registry with the printed or lithographed face of thewrapper. In the end, I found that highly satisfactory results could beobtained by cutting, in a heat resistant rubber surface such as thesurface of a silicone rubber covered roll, a pattern in relief for thesealing areas of the wrapper strip, heating the pattern surface,applying melted adhesive material to the pattern, bringing the outerface of the wrapper strip into rolling contact with the melted adhesivematerial applied to the pattern, and withdrawing the strip from suchrolling contact to produce, upon setting up of the melted adhesivematerial, a wrapper strip having, upon its outer face, predeterminedsealing areas coated with the hot melt adhesive material. By correlatingthis procedure with the operation of conventional packaging machinery itwas found possible to use quite a thick layer of the hot meltadhesive-as could not be done without the greatest diiiiculty if theadhesive-patterned strip were wound into rolls before delivery to thepackaging plant, because the disparity in thickness created by thepattern of relatively thick hot melt adhesive would give a spongy,uneven, roll. With the use of my invention, the thickness of the plasticlayer may, for example, be as great as 2 mils or more. The wrapper stripis brought into contact with the heated silicone rubber pattern rollwith the printed face of the wrapper in registry with the pattern. Themelted adhesive is applied to the pattern by means including anapplicator roll turning in a heated reservoir containing the meltedadhesive material. The reservoir includes cylindrical walls closelysurrounding the surface of the applicator roll, and galleries over whichthe melted adhesive flows to the ends of the applicator roll forlubrication of the roller bearings, re-distribution to the surface ofthe applicator roll and to maintain uniformity in temperature throughoutthe heated reservoir.

Other features and advantages of the invention will appear as thedescription proceeds. In the drawings, wherein I have illustrated thebest mode contemplated by me for carrying out my invention:

FIG. 1 is a face view of the outside of a heat scalable wrapper stripmade in accordance with my invention.

FIG. 2 is a perspective view of a package showing how a wrapper cut fromthe strip of FIG. 1 is applied as an outer sealed wrapping. In this Viewthe final flap folding and sealing operation remains to be performed.

FIG. 3 is a diagrammatic view of my apparatus for making the heatscalable wrapper strip for delivery to a wrapping machine in continuouslengths as the wrapper strip is being prepared.

FIG. 4 is a perspective view of the hot melt applicator roll and rubberpattern roll of the F IG. 3 apparatus, drawn to a larger scale.

FIG. 5 is a detail view taken as indicated at 5-5 in FIG. 4, and showingthe grooved surface of the hot melt applicator roll.

FIG. 6 is a vertical sectional view through the center of the hot meltreservoir and applicator and pattern rolls of the FIG. 3 apparatus.

FIG. 7 is a top view of the hot melt reservoir taken as indicated at 7-7in FIG. 6, and with the hot melt applicator roll removed to show clearlythe flow passages for the hot melt adhesive material.

FIG. 8 is a detail cross sectional view taken as indi cated at 8-45 inFIG. 7, drawn to an enlarged scale.

In FIG. 1, which represents a continuous length of my heat scalablewrapper stripper 9, the section which lies between successive cut linesas represented by the dot dash lines 10 and 11, comprises one completewrapper. As a preferred example of the practice of my invention, it maybe considered that the wrapper strip 9 is a paperbacked aluminum foil.In FIGS. 1 and 2 we see the outer metal face of this strip. The stripwill ordinarily be delivered to my apparatus as a continuous printed web12 (FIG. 3). For example, the printing wil-l usuaily appear within theseveral areas which are exposed on the six sides of the sealed wrapper.The several areas available for printing are designated at 13, theapproximate boundaries of which have been indicated by full lines. Otherareas which become sealed, or partially so, are indicated by dot dashlines, and Within them the outer face of the wrapper strip haspredetermined sealing areas coated with hot melt adhesive material asindicated by the several stippled areas 14. These predetermined sealingareas are applied in registry with the printing. Notice in FIG. 2 thatupon completion of the folding and sealing of the end flaps 15, 16, 17and 18, the sealed areas will extend to the outer edge 19 and diagonalfold edges 20 of the outer end flap 18. With the widely used sealingmethod described at the beginning of the specification, a seal would notbe obtained between the metal to metal contacts at the corners, so thatthe sealing areas do not extend all the way to the edges 20. With theuse of my wrapper the seal can be made to extend to the edges of theflaps and the diagonal fold edges throughout, so the same conditionwould be obtainable at the edges 21, 22 and 23. If desired, however, itis possible to leave one edge unsealed sufiiciently to permit easyopening of the package.

Referring to FIG. 3, I will now describe the general arrangement of theapparatus which is particularly designed as a unit which can be mountedupon a conventional wrapping and sealing machine, taking the printed web12 as delivered from a roll (not shown) and delivering the heat scalablewrapper strip 9 to the wrapping mechanism at the point which may begenerally indicated at 24. In its general arrangement the apparatus formaking the heat scalable wrapper strip for delivery to the wrappingmachine in continuous lengths as the wrapper strip is being prepared,comprises a heat resistant rubber surface such as the surface of asilicone rubber covered roll (designated Rubber Pattern Roll), a pattern25, in relief, for the sealing areas of the wrapper strip cut in saidsurface, means for heating the pattern surface such as an electricalresistance heater 26, means for applying melted adhesive material to thepattern including a hot melt applicator roll and a hot melt reservoir,means for bringing the outer face of the wrapper strip into rollingcontact with the melted adhesive material applied to the pattern,including an idler or drive nip roller 27 and drive roller 28, and meansfor withdrawing the strip 9 from such rolling contact including aninfinitely variable speed reducer and control 29, differential drive andcontrol 30, dancer mechanism 31, and auxiliary drive roller 32. Anelectric eye 33 with associated control mechanism 34 is provided inconjunction with the differential drive control 30 for maintainingregistry between the printed areas of the web 12 and sealing areascoated with hot melt plastic material.

The printed web 12 passes around the drive nip roller 27 in a clockwisedirection, thence around dr-ive roller 28, counterclockwise, intocontact with the melted adhesive material applied to the pattern 25 ofthe rubber pattern roll 6t), and the wrapper strip 9 with itspredetermined sealing areas coated with the hot melt adhesive materialis then drawn around the auxiliary drive roll 32, over idler roller 35,dancer roller 36 and idler roller 37.

The apparatus may be driven from any suitable power source such as theelectric motor '38 which puts the power into the infinitely variablespeed reducer mechanism 29. This mechanism may be of any well-knownconstruction designed for operation from zero speed up to the desiredmaximum. The speed is controlled through a control arm or other device39, indicated diagrammatically by a broken line, in response to theposition of dancer roller 36 carried by hearing blocks 40 slidable upand down in a guideway 41 of frame 42. A weight W suspended from bearingblock 40 applies a predetermined tension to the wrapper strip 9. Thefunction of the dancer roller mechanism is to maintain constant tensionin the wrapper strip as it is delivered to the wrapping machine, and tocorrelate the speed of the hot melt applicator mechanism 61 with thespeed of operation of the wrapping machine. As the speed of operation ofthe wrapping machine increases, it becomes necessary to increase thespeed of the hot melt applicator mechanism. The first effect of theincrease in speed of the wrapping machine is to draw the wrapper strip 9more rapidly through the dancer mechanism which will elevate the dancerroller 36 from the position shown in full lines in FIG. 3, changing theposition of control 39 to increase the speed of the output shaft 43 ofthe speed reducer 29, speeding up the operation of the hot meltapplicator mechanism. An extreme position of dancer roller 36 isindicated by the dot dash line at 36. In practice the movement of thedancer roller may be very slight, and it generally will move to someparticular position and remain there with almost imperceptible changesin position. The effect, as stated, is to maintain the tension in thewrapper strip 9 within negligible limits of variation, while at the sametime correlating speeds of the wrapping and applicator mechanisms.Output shaft 43 is suitably connected in driving relation to the inputshaft 45 of the differential drive mechanism 30 as by means of chain 44and sprockets fixed to the respective shafts.

The hot melt applicator roll 61 is driven from shaft 45 by means of thechain 46. The rubber pattern roll is driven from the hot melt applicatorroll as by means of gears 47 and 48 fixed to the respective shafts. Thegear ratio is such that the pitch diameters of gears 47 and 48 are indirect relation to the diameters of the surfaces of the hot meltapplicator and pattern rolls. This gear ratio may be varied to suitdifferent sizes of pattern rolls as may be needed to accommodatewrappers of different lengths. Drive roller 28 is driven from the outputshaft 49 of differential drive 30 as by means of a chain 50 andsprockets fixed to the output shaft 49 and the shaft 51 of drive roller28 respectively. The function of the differential drive 39 is tocorrelate the speeds of the rubber pattern roll and drive roller 23 soas to maintain registry between the printed surface of web 12 and thepredetermined sealing areas coated with the hot melt material. In theoperation of the apparatus minor variations can occur which would bringthe areas out of proper registry, but this is prevented from happeningby the operation of differential drive 30 and its electrical controlmechanism 34. The electric eye 33 of the control mechanism sees an indexmark 52 (FIG. 1) which may be applied to the web 12 as a part of theprinted pattern. In some cases this mark may merely be the line whichoccurs between dark and light areas of the web as printed. When the eye33 sees this mark at a time when the printed pattern is very slightlyout of registry with the rubber pattern roll, it signals controlmechanism 34 which produces a variation in the relative speeds of shafts45 and 49 of the differential drive. Inasmuch as the generalconstruction and operation of electric eye control mechanisms are wellknown, there is no need to describe these in detail here.

An important feature of my apparatus comprises the provision of arubber, or rubber covered, roll having a pattern for the sealing areasof the Wrapper strip cut in relief in its surface. This pattern 25 isshown clearly in FIG. 4 of the drawings, the depth of the relief havingbeen exaggerated. The pattern is cut into the surface as follows: Theroll is ground to the desired size, cold, the pattern then cut, the rollthen heated up to operating temperature and the heat expansion measured,and finally the pattern is ground off sufiiciently to compensate for theheat expansion. The electrical resistance heater 26 serves to keep thepattern roll at the proper temperature to hold the plastic melt inproper condition for application to the surface of the printed web. Athermostatic control may be provided for this heater. The term rubber ashere employed with reference to the material of the pattern roll, or thematerial of the surface of the roll, is to be understood as includingartificial and synthetic heat resistant rubbers, and equivalentresilient materials. I have obtained excellent results with the use of aroll covered with silicone rubber of a hardness of around 50 durometer.While such a material can be molded only with difficulty, I havediscovered that it is feasible to cut the pattern in relief using asharp knife or other suitable tool.

The hot melt applicator roll 61 which transfers the melted adhesive fromthe reservoir to the surface of the pattern is made with a surfaceespecially adapted to operate in conjunction with a doctor blade 54 soas to apply a measured quantity of the adhesive to the surface of thepattern. In the preferred construction illustrated the hot meltapplicator roll is provided with helical grooves 53. These grooves areV-shaped and may comprise, for example, 90% of the area of the surfaceof the roll. I have had good results with the use of grooves having adepth on the order 0.0032 inch and arranged at an angle of between 30and 45 with respect to a plane passing through the axis of the roll.

Another important feature of my apparatus resides in the provision of anapplicator roll turning in a heated reservoir containing the meltedadhesive material, and the particular construction of the reservoiritself. The reservoir is so constructed that the hot melt applicatorroll can be most efliciently heated by the hot melted adhesive and alsoby radiation from the walls of the heated reservoir. In addition thereservoir is constructed with flow passages and galleries which producea flow of the hot melted adhesive from the reservoir to the applicatorroll and thence, in the area of the doctor blade 54, to galleries andpassages which convey the hot adhesive around the bearings of theapplicator roll to lubricate them, and thence to re-distribute theadhesive to the surface of the applicator roll and to maintainuniformity in temperature throughout the heated reservoir. How theseseveral objectives are accomplished will be understood with reference toFIGS. 6, 7 and 8. The reservoir includes a compartment 55 in which theadhesive is melted down, and a roll compartment 56 of generallycylindrical form closely conforming to the surface of the hot meltapplicator roll 61. The compartments 55 and 56 are connected through apassageway 57 extending longitudinally of compartment 56 beneath theroll 61 .and lateral passages 58, 59 at the ends of passageway 57, andlateral passage 63 at the center of the reservoir. Compartment 56 isenlarged at one side of the applicator roll 61, as at 64, providing aplace to mount the doctor blade 54 and a gallery 65 for accumulation ofexcess amounts of the hot melt plastic as delivered by the applicatorroll to the area of the doctor blade. From the ends of the gallery 65,the hot melt plastic flows through circumferential channels 66 into thespace '67 (FIG. 8) surrounding the bearings 68 for the shaft 69 ofapplicator roll 61. From the bearings the hot melt can flow throughopenings 70 and 71 in the end housing 72 which contains the bearingassembly. The stepped down end 73 of roll shaft 69 projects through .asealed opening in the bearing retainer plate 74 and to this is keyed thesprocket 75 which drives the applicator roll in the manner which hasalready been described.

The body of the reservoir is provided with a series of cored openings 76to receive electrical heating elements such as the resistance heaters77, and one of which may contain a thermocouple 78 providing athermostatic control of the temperature of the walls of the twocompartments of the reservoir. It will be noticed that some of theheating elements are arranged in proximity to the cylindrical surfacesof the roll compartment 56 so that these surfaces will be effectivelyheated and will in turn heat the applicator roll 61 by radiation, and sothat the adhesive will be kept at the right temperature in the spacebetween the surface of the applicator roll and the surface ofcompartment 56. I have obtained good results with the use oftemperatures in the range of about 300 to 400 F. in using commercialgrades of hot melt plastic resin adhesives. The clearance between theapplicator roll and compartment 56 should be very small so that therewill be a minimum amount of plastic at this point to reduce oxidationand keep the adhesive material up to the required temperature. I havefound that excellent results can be obtained if this clearance betweenthe applicator roll and its compartment is kept approximately within thelimits 0.010 inch to 0.015 inch. The hot melt plastic can be introducedin the form of granules, cakes,

blocks, or otherwise, such as the cakes 79 seen in FIG. 6. The bottomsof compartment 56, passageways 58 and 59, and gallery 65 slope inwardlytoward passages 57 and 66, and the bottom of passage 57 slopes inwardlytoward the center of the reservoir and the passageway 63. This aids incirculation of the adhesive to maintain uniform temperature throughoutand to lubricate the bearings of the applicator roll. Also, thearrangement provides a low point for a drain 80 so that the adhesive maybe removed when Operation of the machine is shutdown.

My invention is applicable to both inner and outer wrappings forpackages. Such inner wrappings are sometimes referred to as liners, andI wish the terms wrapper and wrapper strip as used herein and in theappended claims, to be understood as including both inner and outerwrappers.

The hot melt adhesives set up rapidly as the wrapper strip is withdrawnfrom the surface of the pattern roll, and by the time the strip reachesthe wrapping machinery, it will be sutficiently hard to avoid problemsof sticking to or accumulating upon the surfaces of parts of thewrapping machine. This is helpful from a standpoint of maintenance andavoids difliculties which otherwise would be encountered due to defacingof printed areas of the wrappers. As a result it becomes entirelyfeasible to mount my apparatus as a unit directly upon existing wrappingmachines. In this respect my invention provides advantages notobtainable with the use of thermoplastic resins applied with the use ofsolvents as distinguished from the melted form. In the wrapping machineheat is applied to soften the adhesive and furnish the required bond. Ihave found also that a good seal can be obtained with the use of lowerpressures and temperatures than would be required in the case ofthemoplastic adhesives applied to the strip with the use of solvents. Anadditional advantage of my invention is that it furnishes an extremelysimple and effective way for coordinating the operations of producingthe heat sealable wrapper strip in continuous lengths with the operationof the wrapping machines which are in general use at this time.

The terms and expressions which I have employed are used in adescriptive and not a limiting sense, and I have no intention ofexcluding such equivalents of the invention described, or of portionsthereof, as fall within the scope of the claims.

I claim:

1. In apparatus for making a heat scalable wrapper strip for delivery toa wrapping machine in continuous lengths as the wrapper strip is beingmade, means for applying melted adhesive to a pattern roll, saidmeanscomprising a reservoir for the melted adhesive material, a recessin said reservoir to receive an applicator roll, said recess includingcylindrical walls closely surrounding the surface of the applicatorroll, and a gallery extending to the side of said recess foraccumulation of excess amounts of the melted adhesive material carriedout of the cylindrical recess in the reservoir by the applicator roll,said gallery extending to points near the ends of the applicator rolland channels extending from the ends of the gallery to the bearings ofthe applicator roll by virtue of all of which the melted adhesive isconveyed around the bearings of the applicator roll to lubricate them,and thence ire-distributed to the surface of the applicator roll.

2. In apparatus for making a heat scalable wrapper strip for delivery toa wrapping machine in continuous lengths as the wrapper strip is beingmade, means for applying melted adhesive to a pattern roll, said meanscomprising a reservoir for the melted adhesive material, a recess insaid reservoir to receive an applicator roll, said recess includingcylindrical walls closely surrounding the surface of the applicatorroll, means disposed adjacent said cylindrical walls for heating theadhesive lying Within the space where the cylindrical walls closelysurround the surface of the applicator roll and for heating theapplicator roll by radiation from the cylindrical walls,

and a gallery extending to the side of said recess for accumulation ofexcess amounts of the melted adhesive material carried out of thecylindrical recess in the reservoir by the applicator roll, said galleryextending to points near the ends of the applicator roll and channelsextending from the ends of the gallery to the bearings of the applicatorroll by virtue of all of which the melted adhesive is conveyed aroundthe bearings of the applicator roll to lubricate them, and thencere-distributed to the surface of the applicator roll for heating and tomaintain 10 uniformity in temperature throughout the reservoir.

References Cited in the file of this patent UNITED STATES PATENTS AllenJan. 4, 1898 Sevigne Dec. 6, 1921 Sturm Dec. 23, 1952 Pavlic May 26,1953 Zinn Nov. 17, 1953 Scholl Jan. 3, 1956 Harmon 'Feb. 12, 1957 KellyApr. 2, 1,957

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3,030,915 April 24, 1962 Arthur Vernon Shannon It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

In the nt, line 1, name of inventor, for 'Arthur Vernon Channon" readArthur Vernon Shannon column 6 line 34, for "themoplastic" readthermoplastic line 3, for "space" read spaces Signed and sealed this25th day of September 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID D Attesfing Office Commissioner of Patents

